Countercurrent extraction column having mixer blades adapted for rotation and vertical oscillation



y 1967 L. ZIEHL 3,318,668

COUNTERCURRENT EXTRACTION COLUMN HAVING MIXER BLADES ADAPTED FOR ROTATION AND VERTICAL OSCILLATION Filed Aug. 15, 1963 Fig/ HEAVY PHASE 4 LIGHT PHASE OUTLET 5-L mwr PHASE llYLET H54 vy PHASE 7 00 mar INVENTOF? LUDWI6' ZIE H L.

Y B M'MLMAMA,

United States Patent 4 Claims. (c1. 23-270 This invention relates to an extraction column with movable mixer fittings.

Liquid-liquid extraction has achieved great importance during the last decade in technical chemical processes for isolating substances from mixtures of substances. Associated therewith is the development of apparatus, the purpose of which, in its various constructional forms, is to obtain optimum efiiciency of the installation. Among the numerous previously proposed extraction arrangements, there have been columns having movable mixer fittings. These fittings are connected fast to a driving member and are set in rotation by the latter or periodically reciprocated axially of the column.

It has now been found that a high efficiency is achieved in a column with mixer fittings if a horizontal rotational movement is superimposed on the motion of fittings which are reciprocating axially by the driving member. Thus, one point on the rim of the mixer fitting then describes an ascending and then descending helical line.

This movement results in an intimate mixing of the two phases which are in countercurrent and counteracts the rim movement of columns. By the special design of the mixer fittings e.g. as a star or impeller wheel with a certain pitch angle of the blades, the movement of one phase can be promoted and the movement of the other phase can be retarded. 'By this means, it is possible to obtain different residence times of the separate phases in the extraction column.

By varying the spacing of the mixer fittings it is possible to adapt the mixing effect to the actual density conditions of the phases and their surface tensions over the length of the extraction column. For carrying out an extraction in best possible manner, the shapes of the mixer fittings, the spacings of the mixer fittings from one another, the frequency, amplitude and rotational movement of the mixer fittings are matched to one another. The spacing of the mixers is approximately of the same order of magnitude as the diameter of the column, but can also amount to a multiple of this value. The frequency of the mixer is about 50 to 500 and preferably about 100 strokes per minute with an amplitude which is about half to one and a half times the spacing of the mixer fittings from one another and is preferably just about as large as the mixer spacing. The periodic reciprocating movement of the mixer has superimposed thereon a rotational movement of 30 to 200 revolutions per minute and preferably 60 to 120 revolutions per minute.

For an optimum extraction operation of the column according to the invention, the phase conditions and the associated flow velocities in the column are also of importance. In practical operation, the readiness of the mixtures to form emulsions, often due to traces of impurities, plays an important part. However, it has been found that the extraction column according to the invention can easily be adapted to the given problems and provides values which can be completely reproduced and extrapolated. The extraction column according to the invention is particularly suitable for the treatment of solutions which cannot be filtered and also for extractions in which solid substances are separated out. Due to the lack of stationary fittings in the cylindrical part of the column and the three-dimensional movement of the mixer fittings, there is no possibility of deposition of solid material.

The operation of the column will be explained with reference to the accompanying drawings: in which FIG- URE l is a diagrammatic view showing the entire col umn with the driving members, and FIGURES 2 and 3 show different forms of mixer fittings.

Arranged centrally in a tubular extraction column 1 is a driving shaft 2, to which the mixer devices 3 arerigidly connected. The heavy phase is supplied to the column at 4and the light phase at 5. The discharge of the light phase takes place at 6 and the discharge of the heavier phase at 7. The required frequency and amplitude of the mixer devices are set by regulating gear 9, which drives an adjustable eccentric 10. Disposed beneath the eccentric drive is a ball joint mounting 8 and below the latter there is driving means 11 for the rotational movement of the mixer fittings. This rotational movement is advantageously transmitted from a driving motor through a worm and wormwheel to the driving shaft of the mixer fittings. The use of adjustable gearing facilitates the bringing of the column up to maximum efficiency and the adjustment of the phase equilibrium. The column should advantageously be run about 10% below the flood limit, i.e. the immobilising of the phases.

For example, with the removal of phenol from waste water with solvent naphtha, the frequency of the vertical mixer movement was 50 strokes per minute, while with the extraction of uranyl nitrate solutions, it was 60 strokes per minute. With the extraction of uranyl nitrate solutions from aqueous solutions with tri-butyl phosphate, the loading of the column and the yield could be increased as compared with a pulsating column. The H.T.U. (height theoretical stage) was between 0.5 and 0.8 m. with uranium concentrations in the aqueous solutions of 3 00 g. of U per litre, and the yield with 3-4 stages was higher than 99.9%.

What is claimed is:

1. An extraction column containing no plates or baffles for countercurrent liquid-liquid extraction consisting of an elongated cylindrical extraction chamber, first supply means for supplying the heavy phase liquid at the upper part of the extraction chamber, second supply means for supplying the lighter phase liquid at the lower part of the extraction chamber, first means for discharging the lighter phase liquid from the upper part of the extraction chamber, said first discharging means being provided above the inlet of said first supply means, second means for discharging the heavier phase liquid from the lower part of the extraction chamber, said second discharging means being provided below the inlet of said second supply means for supplying the lighter phase liquid, a vertical drive shaft extending axially the length of the column and outwardly through the top of said column, a plurality of horizontal star-shaped mixing fittings having a plurality of pointed arms extending therefrom, said fittings being mounted on said shaft below the inlet of said first supply means and spaced from said first and second discharging means so as to provide a settling and separating space for the lighter and heavier phase liquids after mixing, first drive means connected to the top of said drive shaft for imparting vertical reciprocatory motion to the drive shaft, and second drive means connected to the top of said drive shaft for imparting rotary motion to the drive shaft while the drive shaft is reciprocating vertically, said mixing blades: being spaced axially along said drive shaft one from the other by at least about the diameter of the extraction chamber, said first drive means being adapted to impart to the drive shaft a vertical reciprocatory motion of an amplitude of about one half time to one and one half times of the spacing of the mixing blades from one another with a frequency of about 50 strokes to about 500 strokes per minute, said second drive means being adapted to impart to the mixing blades a rotational movement of about 30 revolutions to about 200 revolutions per minute.

2. The extraction column according to claim 1, Wherein the arms of said horizontal fittings are fixed at a predetermined pitch angle with respect to the plane of said fitting star-shaped.

3. The extraction column according to claim 1, wherein said arms are in the form of impellers.

4. The extraction column according to claim 1, wherein the first drive means are adapted to impart to the drive shaft a vertical reciprocatory motion of an amplitude as large as the spacing of the mixing blades from each other.

41 References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 5/ 1957 Great Britain. 10/ 1961 Russia. 11/ 1918 Switzerland.

15 NORMAN YUDKOFF, Primary Examiner.

S. EMERY, Assistant Examiner. 

1. AN EXRACTION CONTAINING NO PLATES OR BAFFLES FOR COUNTERCURRENT LIQUID-LIQUID EXTRACTION CONSISTING OF AN ELONGATED CYLINDRICAL EXTRACTION CHAMBER, FIRST SUPPLY MEANS FOR SUPPLYING THE HEAVY PHASE LIQUID AT THE UPPER PART OF THE EXTRACTION CHAMBER, SECOND SUPPLY MEANS FOR SUPPLYING THE LIGHTER PHASE LIQUID AT THE LOWER PART OF THE EXTRACTION CHAMBER, FIRST MEANS FOR DISCHARGING THE LIGHTER PHASE LIQUID FROM THE UPPER PART OF THE EXTRACTION CHAMBER, SAID FIRST DISCHARGING MEANS BEING PROVIDED ABOVE THE INLET OF SAID FIRST SUPPLY MEANS, SECOND MEANS FOR DISCHARGING THE HEAVIER PHASE LIQUID FROM THE LOWER PART OF THE EXTRACTION CHAMBER, SAID SECOND DISCHARGING MEANS BEING PROVIDED BELOW THE INLET OF SAID SECOND SUPPLY MEANS FOR SUPPLY THE LIGHTER PHASE LIQUID, A VERTICAL DRIVE SHAFT EXTENDING AXIALLY THE LENGTH OF THE COLUMN AND OUTWARDLY THROUGH THE TOP OF SAID COLUM, A PLURALITY OF HORIZONTAL STAR-SHAPED MIXING FITTINGS HAVING APLURALITY OF POINTED ARMS EXTENDING THEREFROM,SAID FITTINGS BEING MOUNTED ON SAID SHAFT BELOW THE INLET OF SAID FIRST SUPPLY MEANS AND SPACED FROM SAID FIRST AND SECOND DISCHARGING MEANS SO AS TO PROVIDE A SETTLING AND SEPARATING SPACE FOR THE LIGHTER AND HEAVIER PHASE LIQUIDS AFTER MIXING, FIRST DRIVE MEANS CONNECTED TO THE TOP OF SAID DRIVE SHAFT FOR IMPARTING VERTICAL RECIPROCATORY MOTION TO THE DRIVE SHAFT, AND SECOND DRIVE MEANS CONNECTED TO THE TOP OF SAID DRIVE SHAFT FOR IMPORTING ROTARY MOTION TO THE DRIVE SHAFT WHILE THE DRIVE SHAFT IS RECIPROCATING VERTICLLY, SAID MIXING BLADES BEING SPACED AXIALLY ALONG SAID DRIVE SHAFT ONE FROM THE OTHER BY AT LEAST ABOUT THE DIAMETER OF THE EXTRACTION CHAMBER, SAID FIRST DRIVE MEANS BEING ADAPTED TO IMPART TO THE DRIVE SHAFT A VERTICAL RECIPROCATORY MOTION OF AN AMPLITUDE OF ABOUT ONE HALF TIME TO ONE AND ONE HALF TIMES OF THE SPACING OF MIXING BLADES FROM ONE ANOTHER WITH A FREQUENCY OF ABOUT 50 STROKES TO ABOUT 500 STROKES PER MINUTE, SAID SECOND DRIVE MEANS BEING ADAPTED TO IMPORT TO THE MIXING BLADES A ROTATIONAL MOVEMENT OF ABOUT 30 REVOLUTIONS TO ABOUT 200 REVOLUTIONS PER MINUTE. 